The present invention relates to dynamic flight simulators used for familiarizing pilots with the force and motion environment associated with actual flight of modern high performance aircraft; and more particularly to a control system for the simulator's force and motion platform for enhancing flight realism to the occupant with regard to his perception and response to the linear and angular motions generated by the platform.
A ground-based dynamic flight simulator provides a safe and convenient research facility for test and evaluation of new concepts in crew station design, cockpit displays and controls, restraint systems, aerodynamic configurations and handling qualities as well as conducting training in pilot procedures in the accleration or G-environment in which they are designed to be utilized.
A human centrifuge such as disclosed in U.S. Pat. No. 3,732,630 to Richard J. Crosbie et al provides one type of motion base for these purposes. A ten-foot diameter spherical gondola is mounted in a two-gimbal drive system at the end of a rotating arm, and an aircraft cockpit complete with an out-the-window visual display system, instrumentation, and flight controls similar to those in a given aircraft, is housed within the gondola. The angular motion of the arm and the two angular rotations of the gondola within the gimbals provide three controllable degrees of freedom which are normally used to approximate the total G-force imparted on a pilot by the six degrees of freedom of the aircraft in actual flight. With only three degrees of freedom, however, it becomes physically impossible to match precisely both the linear forces and angular motions of the gondola with those of the aircraft. Of course it is contemplated that other types of motion bases may be used with commensurate limitations in their ability to match the total dynamic environment of the aircraft.
The mismatch is not critical in open loop physiological studies where a wide variety of complex multi-directional G-force profiles on a subject are generated from a remote preprogrammed control system. However, when the centrifuge is used as a force and motion base with the pilot placed in a closed control loop the mismatch is not acceptable, especially when he is required to "fly" through maneuvers involving periods of transient G-forces. Rapid rotations of the two gimbals and the centrifuge arm required to simulate precisely the G-force environment of such maneuvers result in angular motions which are totally unrelated to those in the actual aircraft. This deception produces a conflict in the pilot's sensory response making the simulator difficult to "fly" and severely limiting for pilot-controlled flight simulation studies.
Total simulation is particularly difficult in the flight regime slightly above +1G because of the large gimbal motions required, and is virtually impossible between -1G and +1G due to the ever present acceleration of gravity. Consequently, simulation requirements were relaxed for rapidly changing G-forces in the region slightly above and below +1G, but still enabling the simulator to generate forces having similar debilitating and disorienting effect on the pilot as those produced by the actual aircraft.